In the air conditioner market, two electronic expansion valves are employed since an indoor unit is disposed far away from an outdoor unit of an air conditioner. In addition, each of the two electronic expansion valves is required to be connected to a respective one-way valve in parallel to improve the system efficiency to the greatest extent. The schematic diagram of the system of the air conditioner is shown in FIG. 1, and the working principle is briefly described as follows.
The refrigerating operation is described as follows. Gaseous refrigerant with high temperature and high pressure which is discharged from a gas discharge pipe of a compressor 7′8 passes through, in turn, a connecting pipe D and a connecting pipe E of a four-way valve 7′1, an outdoor heat exchanger 7′2 (releasing heat by condensation), a first one-way valve 7′4 (here, a first electronic expansion valve 7′3 does not function to regulate the flow), and a second electronic expansion valve 7′5 (here, a second one-way valve 7′6 is closed, and the second electronic expansion valve 7′5 functions to regulate the flow), and finally enters into an indoor heat exchanger 7′7 to be evaporated, so as to absorb heat to realize the refrigerating function. Here, the second electronic expansion valve 7′6 is close to the indoor heat exchanger 7′7, thus the heat loss may be reduced (if the electronic expansion valve is too far away from the evaporator, the liquid refrigerant with low temperature and low pressure which is discharged from the electronic expansion valve is apt to be gasified, which not only causes heat loss, but also results in significant reduction of the utilization rate of the evaporator). Also, if the refrigerant with medium temperature and high pressure which is discharged from the outdoor heat exchanger 7′2 passes through the first electronic expansion valve 7′3, a throttling effect may still occur even when the expansion valve is fully opened, which reduces the pressure of the refrigerant, and then when the refrigerant is transferred to the second electronic expansion valve 7′5, it is apt to be gasified partly, therefore the throttling effect of the electronic expansion valve is adversely affected, and the system efficiency is reduced.
The heating operation is described as follows. Gaseous refrigerant with high temperature and high pressure which is discharged from the gas discharge pipe of the compressor 7′8 passes through, in turn, the connecting pipe D and a connecting pipe C of the four-way valve 7′1, the indoor heat exchanger 7′7 (releasing heat by condensation), the second one-way valve 7′6 (here, the second electronic expansion valve 7′5 does not function to regulate the flow), the first electronic expansion valve 7′3 (here, the first one-way valve 7′4 is closed, and the first electronic expansion valve 7′3 functions to regulate the flow), and finally enters into the outdoor heat exchanger 7′2 to be evaporated, so as to absorb heat to realize the refrigerating function. Here, the first electronic expansion valve 7′3 is close to the outdoor heat exchanger 7′2, thus the heat loss may be reduced (if the electronic expansion valve is too far away from the evaporator, the liquid refrigerant with low temperature and low pressure which is discharged from the electronic expansion valve is apt to be gasified, which not only causes heat loss, but also results in significant reduction of the utilization rate of the evaporator). Also, if the refrigerant with medium temperature and high pressure which is discharged from the indoor heat exchanger 7′7 passes through the second electronic expansion valve 7′5, the throttling effect may still occur even when the expansion valve is fully opened, which reduces the pressure of the refrigerant, and then when the refrigerant flows to the first electronic expansion valve 7′3, it is apt to be gasified partly, therefore the throttling effect of the electronic expansion valve is adversely affected, and the system efficiency is reduced.
However, in the current market, some customers require to integrate the one-way valve with the electronic expansion valve, so as to reduce the numbers of parts and solder joints, and to further improve the reliability of the system.
In view of this, in the conventional technology, an electronic expansion valve with function of a one-way valve is disclosed in Japanese Patent Application Publication No. 2009-287913. Reference may be made to FIGS. 2 and 3. FIG. 2 is a schematic view showing the structure of an electronic expansion valve in the conventional technology which is performing a flow regulation when the refrigerant flows forwards; and FIG. 3 is a schematic view showing the structure of the electronic expansion valve in the conventional technology, wherein the electronic expansion valve is opened when the refrigerant flows reversely.
As shown in FIGS. 2 and 3, the electronic expansion valve in the conventional technology includes a valve seat 1′. The valve seat 1′ is provided with a main valve cavity 1′1, a transverse connecting port 1′2 and a vertical connecting port 1′3, and an opening at an upper end of the vertical connecting port 1′3 forms a main valve port 1′31. A valve core seat 2′ is provided inside the main valve cavity 1′1, and a circumferential side wall of the valve core seat 2′ abuts against an inner circumferential side wall of the main valve cavity 1′1, thus the valve core seat 2′ is guided by the main valve cavity 1′1 and may reciprocate along an axial direction of the main valve cavity 1′1, so as to open or close the main valve port 1′31. Further, as shown in FIGS. 2 and 3, the valve core seat 2′ is provided with a secondary valve cavity 2′1, and a valve core valve port 2′2 in communication with the secondary valve cavity 2′1, and a valve needle component 3′ extends into the secondary valve cavity 2′1 and reciprocates along an axial direction of the secondary valve cavity 2′1, so as to open or close the calve core valve port 2′2. Furthermore, as shown in FIGS. 2 and 3, the circumferential side wall of the valve core seat 2′ is further provided with a communicating hole 2′3 in communication with the secondary valve cavity 2′1, and the communicating hole 2′3 faces the transverse connecting port 1′2, to allow the secondary valve cavity 2′1 to communicate with the transverse connecting port 1′2.
In addition, as shown in FIGS. 2 and 3, the transverse connecting port 1′2 is connected to a transverse connecting pipe 4′1, and the vertical connecting port 1′3 is connected to a vertical connecting pipe 4′2. The flow of the refrigerant fluid from the transverse connecting pipe 4′1 to the vertical connecting pipe 4′2 (i.e., a side of the transverse connecting port 1′2 is a high pressure zone, and a side of the vertical connecting port 1′3 is a low pressure zone) is defined as a forward flow, and the flow of the refrigerant fluid from the vertical connecting pipe 1′3 to the transverse connecting pipe 1′2 (i.e., the side of the vertical connecting port 1′3 is a high pressure zone, and the side of the transverse connecting port 1′2 is a low pressure zone) is defined as a reverse flow. The valve needle component 3′ is connected to a screw rod 5′1, and the screw rod 5′1 cooperates with a nut 5′2 by screw threads. In such structure, a magnet 6′2 is rotated under the action of a magnetic field of a coil 6′1; and then the screw rod 5′1 is rotated and axially reciprocates due to the screw-thread fit with the nut 5′2, thereby driving the valve needle component 3′ to reciprocate axially to open and close the valve bore valve port 2′2.
As shown in FIG. 2, when the refrigerant flows forward, the side of the transverse connecting port 1′2 is the high pressure zone, and the side of the vertical connecting port 1′3 is the low pressure zone. The valve core seat 2′ moves downward under the action of a pressure difference of the refrigerant, thereby closing the main valve port 1′31. On this basis, the refrigerant enters into the secondary valve cavity 2′1 from the transverse connecting port 1′2 through the communicating hole 2′3, the valve needle component 3′ opens the valve core valve port 2′2, and the refrigerant entered into the secondary valve cavity 2′1 flows to the vertical connecting port 1′3 via the valve core valve port 2′2, and in turn flows into the vertical connecting pipe 4′2. In this operation, the screw rod 5′1 moves axially to allow the valve needle component 3′ to regulate an opening of the valve core valve port 2′2, thereby achieving an object of flow regulation of the electronic expansion valve.
As shown in FIG. 3, when the refrigerant flows reversely, the side of the vertical connecting port 1′3 is the high pressure zone, and the side of the transverse connecting port 1′2 is the low pressure zone. Here, the valve core seat 2′ is pushed to move upward under the action of the pressure difference of the refrigerant, thereby opening the main valve port 1′31. The refrigerant flows through the main valve port 1′31, the main valve cavity 1′1 and the transverse connecting port 1′2 to the transverse connecting pipe 4′1, thereby achieving the function of one-way communication of the one-way valve.
However, the above electronic expansion valve in the conventional technology has the following defects.
Firstly, as shown in FIG. 2, when the refrigerant flows forward, the side wall of the valve core seat 2′ faces the transverse connecting port 1′2, thus the circumferential side wall of the valve core seat 2′ may be impacted by the refrigerant with high pressure. When the pressure of the refrigerant fluctuates, an eccentricity of the valve core seat 2′ may be caused, thus the valve core seat 2′ cannot tightly seal the main valve port 1′31, which causes a large internal leakage, and adversely affects the working performance of the system. Furthermore, the eccentricity of the valve core seat 2′ may cause interference between the valve needle component 3′ and the valve core valve port 2′2.
Secondly, as shown in FIG. 3, when the refrigerant flows reversely, the communicating hole 2′3 always remains open, thus a part of the refrigerant may enter into the secondary valve cavity 2′1 via the communicating hole 2′3. And, the refrigerant entered into the secondary valve cavity 2′1 will apply a downward action force on the valve core seat 2′, thus only when the pressure of the refrigerant from the transverse connecting port 1′2 is large enough, the main valve port 1′31 can be opened stably, therefore the sensitivity of the opening of the main valve port 1′31 is not high.